1. Field of the Invention
The invention relates to a floor covering made up of at least two layers bonded to one another, including a bottom layer of electrically conductive rubber arranged under a light-colored top layer of rubber, where the top layer is interrupted in partial areas distributed over its area in a pattern, and formed by electrically conductive rubber there.
2. Description of Related Art
Such a floor covering is known from European Patent 0 105 074 B1. It is made up of two contrast-colored layers of rubber, arranged one on top of the other, where the bottom layer is conductive and the top layer is not conductive. It is produced in that the material of the top layer is pre-hardened by partial vulcanization before it is pressed, and removed in the stated area regions, and subsequently placed as a layer onto the layer of softer, non-vulcanized rubber, that pressing takes place in such a way that the material of the bottom layer completely fills the area regions, and that the structure obtained in this way is permanently bonded and solidified by a subsequent vulcanization process. In this way, it can be used, in excellent manner, as a floor covering that can be widely varied with regard to the colored structure of its surface, and makes it possible to divert electrical voltages that occur on the top side, via the bottom side. However, production of such a floor covering is complicated in that removal of the top layer in the partial regions requires the use of a cutting process. This is not only expensive, furthermore it results in restrictions with regard to the geometrical structure and distribution of the partial regions.
From German Patent 36 23 795, it is known to add a fraction of hardened rubber particles with a particle size of 0.1 to 1 mm, in an amount on the order of 5 to 60 parts, to a rubber mixture, as an admixture to 100 parts, in each instance, before the mixture is hardened, in order to produce a defined bumpy surface. This imparts a good grip to a handle made of rubber, for example.
It is an object of the invention to develop a floor covering of the type stated above, in such a way that there is a better possibility of structuring the appearance of the surface in terms of design, while at the same time making it easier and more inexpensive to produce.
These and other objects of the invention are achieved by a floor covering made up of at least two layers bonded to one another, including a bottom layer (2) of electrically conductive rubber arranged under a light-colored top layer (1) of rubber, where the top layer (1) is interrupted in partial areas distributed over its area in a pattern, and only there is formed by electrically conductive rubber, wherein the top layer (1) is produced from a powder (1.1) of first particles (1.2) that are light in color and made of electrically insulating rubber, as well as second particles (1.3) embedded therein, which are made of electrically conductive, at least partially vulcanized rubber; the second particles (1.3) have a diameter D, determined by screen analysis, that is at least as great as the thickness D1 of the top layer and at most as great as the total of the thicknesses of the top layer and the bottom layer D2; the first (1.2) and the second (1.3) particles are pressed together and to the bottom layer (2), without pores, and bonded by vulcanization; and at least one of the second particles (1.3) is present per area unit of the floor covering of 31.7 cm2, with the proviso that a maximum of 50% of the total area of the floor covering is taken up by the area of the second particles (1.3).